1. Field of the Invention
This invention relates to a method of monitoring the progress and pattern of a combustion or flame front being advanced through a combustible subterranean carbonaceous stratum, and thereafter controlling the progress of said flame front. In particular, this invention relates to a method of monitoring both the vertical and lateral movement of an underground flame front and injected gases into the vicinity of the combustion area to control the flame front. More particularly, this invention relates to a method of monitoring the pattern and spatial orientation of a flame front during in situ retorting of oil shale and injecting and controlling the flow of fuel or flue gases into the retort to control the speed, extent and uniformity of the flame front in the retort.